In a method of manufacturing a semiconductor device, if the underlying layer of an etching target layer is damaged when etching the etching target layer, the reliability of the semiconductor device may degrade. For example, when ensuring an electrical contact between interconnection layers, a contact hole needs to be formed in an insulating layer between the interconnection layers. This contact hole is formed using an anisotropic reactive etching method such as RIE (Reactive Ion beam Etching).
However, when a fluorine-based gas is used as the etching gas for the contact hole, unintended overetching occurs due to a low selection ratio of the insulating layer serving as the etching target layer with respect to the interconnection layer serving as the underlying layer, and an electrical contact failure occurs so that, for example, the contact hole extends through the interconnection layer.
To prevent the electrical contact failure between the interconnection layers, a technique of etching the insulating layer as the etching target layer at a high selection ratio with respect to the interconnection layer as the underlying layer is necessary.